Mechanism for drawing roving of different staple lengths



W. NAEGELI Nov. 30, 1954 MECHANISM FOR DRAWING ROVING OF DIFFERENT STAPLE LENGTHS Filed Jan. 27, 1949 United States Patent Ofifice 2,695,428 Patented Nov. 30, 1954 MECHANISM FOR DRAWING ROVING OF DIFFERENT STAPLE LENGTHS Werner Naegeli, Winterthur, Switzerland, assignor to Actrengesellschaft Joh. Jacob Rieter & Cie., Winterthur, Switzerland Application January 27, 1949, Serial No. 73,026 Claims priority, application Switzerland July 10, 1948 10 Claims. (Cl. 19-131) This invention relates to the spinning of roving and in particular, to a method of drawing roving from raw fibrous materials of different staple lengths with a constant distance between the rollers, and to a drawing mechanism for carrying out said method.

e main drawing field in known high draft drawing mechanisms commonly lies between the last two pairs of rollers at the delivery end of the drawing mechanism. It is generally considered that the length of the drawing mechanism, that is, the gripping distance, should correspond approximately to the longest fibres present in the roving, so that the distance between the rollers must always be adapted, by adjustment, to the length of fibre to be treated in order to obtain the greatest efficiency from the drawing mechanism. Such adjustments always cause a loss of time and necessitate great care and accurate machining of all the parts in order that the rollers of the drawing mechanisms of the entire frame will always be parallel.

It is known to support the roving in the drawing field. Therefore, in order to regulate the drawing out of the fibres from the drawing field, a further pair of rollers, comprising a fluted roller and a light slip roller mounted thereon, has been provided near the front pair of rollers. The same purpose is achieved by means of travelling belts with slip rollers mounted thereon or guide belts co-operating in pairs. Such means serve the purpose of keeping the shorter floating fibres, which are not gripped at either end, at the speed of delivery of the preceding pair of rollers, until they are taken up and withdrawn at the delivery end by the following more rapidly rotating pair of rollers.

Careful consideration of the drawing processes shows that the drag exerted on the fibres by the support means, preferably, should decrease gradually in the forward direction from the maximum value at the gripping point of the rear pair of rollers, and finally be reduced, as near as possible, to zero at the gripping point of the pair of delivery rollers. It is therefore not correct to brake the speed of the outgoing fibres only at a single point, as is the case, for example, with a slip roller and sometimes also with known two-belt drawing mechanisms. In the case of drawing mechanisms of the last mentioned type, it has been found that the belts bulge out, owing to internal tension, in the center between the rear gripping point and the front deflecting means, and no longer hear one against the other. The drag or braking action is thus, only exerted upon the fibres along one line, as in the case of slip rollers. This is why in such drawing mechanisms for drawing roving of different length staples, different roller spacings and consequently traveling belts of different lengths have been employed.

Having regard to the above mentioned facts, the method according to the present invention provides new means, in that the drag exerted on the fibres by the support means provided between the gripping points, which drag decreases in the direction of the front pair of drawing rollers, is varied in accordance with the length of the staple fibres, while the overall length of the drawing field is always maintained constant.

The means employed to carry out this method, preferably comprises a drawing mechanism with two cooperating endless traveling belts as guide means, the arrangement being such that the relative position of the separately mounted front guide means of the belts is so varied, for example, from a central point that the configuration of the path of the traveling belt which guides the fibres, and consequently the drag exerted on the fibres, also is varied.

An embodiment of my present invention is illustrated, by way of example, in the accompanying drawings, in which Fig. 1 shows a two-belt drawing mechanism in crosssection, adjusted for drawing longstaple fiibres,

Fig. 2 shows the same drawing mechanism, adjusted for drawing short fibres, and

Fig. 3 is a diagrammatic illustration of the gripping forces exerted on the fibres, which forces cause the drag.

The three-roller stretching mechanism shown in Figs. 1. and 2 comprises the bottom rollers 1, 2 and 3 and their associated top rollers 4, 5 and 6. The top roller 5 is located somewhat forwardly of the corresponding bottom roller 2. The main drawing field of the drawing mechanism is situated between the pairs of rollers 1, 4 and 2, 5. Within the range of said main drawing field an endless upper endless traveling belt 7 and a lower traveling belt 8 are arranged to influence the drawing action. A weighting saddle or link 11, which is fixed in space and interconnects the top roller spindles 9 and 10 and is guided by means not shown, supports on both sides guide means for the upper traveling belt 7. This guide means comprises a guide member 12 which extends along one reach of belt 7 to a point near the top rollers 5 and is provided with a convex lower surface at its rear portion which recedes from belt 7 in the forward direction toward the front rollers, and forwardly of said convex portion the guide is provided with a concave recess. The front edge of guide 12 is rounded and serves as a reversing rail for belt 7. Two. extensions 13 of the guide member 12 (of which only the one beyond the section line is shown in the drawing) serve for laterally guiding the upper travel ing belt 7. The lower traveling belt 8 is guided laterally by curved extensions 15 of column members 14, the said extensions 15 resting on bottom roller 2. The said column members are interconnected by a brace 16 to form a guide cage for the lower traveling belt, which guide cage bears through the column members 14 on a vertically adjustable member 17. The said cage supports a reversing pulley 18 near the front bottom roller 1. A tensioning roller 19 guided between the bracket members 14, serves to tighten the lower belt 8.

The roving 20 drawn in by the pair of rollers 3, 6 as shown in Fig. 1, is acted upon at the gripping point of the rollers 2 and 5 by the two co-operating traveling belts 7 and 8 and is conveyed forwards between the latter, whereupon the front rollers 1, 4 deliver the fibres coming within their range.

The belt 8, tightened by the tensioning roller 19, is curved around the upper belt 7 in accordance with the amount by which the top roller 5 is positioned forwardly of its associated bottom roller 2. The belt 8 therefore exerts gripping forces on the traveling roving. When the deflection of the two belts ceases, as seen in the direction of travel of the roving, the upper belt 7 bears against the lower belt 8 only by reason of its own rigidity and as a result of its being only guided by the guide part 12. The gripping forces exerted on the roving and causing a drag on the fibres reach a maximum value precisely at the gripping point of the rollers 2 and 5, whereafter they decrease and are finally reduced to zero at the forward line of contact of the two traveling belts.

In Fig. 3, the approximate variation of these gripping forces between the two gripping points A and B of the pairs of rollers 1, 4 and 2, 5, respectively is represented by the curve I, the distanceof any point in the curve from thehorizontal a indicating the extent of the gripping force acting at this point. Such a variation of the gripping forces is suitable for drawing long-staple fibers 20'. The longest of the fibers here correspond approximately to the distance between the rollers. The fibres floating between the gripping points A and B, after they have been freed from the gripping action of the pair of rollers 2 and 5, continue to be held by the belts 7, 8i and cannot be carried along by the fibres which have already been gripped by the pair of rollers 1, 4 and which move at a' greater speed than the belts.

According to Fig. 2, the drawing mechanism is adjusted for drawing short fibres 21' (Fig. 3), the distance between the pairs of rollers 1,, 4 and 2, 5, however, being unchanged. The difference as compared with Fig. l resides in he fa t tha the ver ically adj s l pp 17 is lifted in the direction f. the arrow in Figy means not shown. The cage guiding the lower traveling belt 8, here rotates about the bottom roller 2 clockwise, as viewed in Fig. 2, whereby the deflecting roller 18 supported by the cage enters the concave recess of the guide member 12. As shown in Fig. 2, the deflection of the two belts 7 and 8, due to the relative adjustment of guide 12 and pulley 18, is increased. Consequently, the lower tensioned belt 8 exerts an increased gripping force on the fibres in the region of the guide member 12. This gripping action decreases in the forward direction, and diminishes to zero at the delivery point of the two belts. The dotted curve II in Fig. 3 shows the approximate variation of the gripping forces exerted on the fibres with the deflecting roller 18 lifted. The displacement has an prOXimately the same effect on the fibres as if the pair of rollers 2, 5 were displaced further forward until the gripping point B of the rollers 2, 5 coincided with the line'through C. With the adjustment shown in Fig. 2, the gripping forces, that is the breaking action exerted on the fibres, i already so great on the line through C as to ensure a sufiicient gripping of the fibres, The drawing action therefore takes place only on the section between A and C, as is required by the short staple of the fibres and in. contras to what is the case with the adjustmeri of h drawing me hanism as shown in g- 1- Between the extreme adjustments of the drawing mechanism as shown in Figs. 1 and 2, any desired adjustment jiisbpossible for purposes of adaptation to the staple of the res. mediate position of the deflecting roller 18, a variation of the gripping forces as shown by curve III can be obtained, which is suitable for spinning fibres 22 of medium staple length.

In the drawing, mechanism described, the draft is kept small by the forwardly decreasing gripping action, and consequently the braking action, exerted on the fibres by the traveling belts. The driving power is reduced to a minimum.

Ifurthermore, natural and artificial fibres of the most varied staple lengths can be properly drawn with constant d stances between the rollers. The time-wasting and compl cated adjustment of the roller bearings is avoided. Moreover, a considerable reduction in the cost, of manufacture of these parts of the stretching mechanism is effected, while the stretching mechanism can be simply ad usted to the staple to be spun by adjustment of the support on which the cages of the lower belts bear. This is effected from a central point of the machine for all spinning points. stretching mechanism can also be effected with the machine n operation, so that favorable operating conditions can readily be obtained.

. What I claim and desire to secure by Letters Patent,

l. A drawing frame for drawing roving, comprising guide means for the roving, said guide means comprising two endless belts having adjacent run portions between which the roving is guided and moving in the same direct1on as the roving, individual support means for each belt whlch is looped around its support means, one of said support means comprising a roll rotating on a stationary ax s, the second support means having a roll resting through the lntermediary of the belt extending about it on the belt supported by the roll rotating on the. stationary axis, the roving entering said guide means. between s i r lls, an belt guide m m r xtending in. h travel direction of he ro ing; from the roll of sai s cond support means, said first support means comprising a secon 11 p c d in. the, travel. direction of the ro ing from n ppor ed o swing about; id stationary axis toward and from said belt guide member.

A drawing frame for drawing roving as defined in 91. 1, and belt guide member having a recess extendng, transversely to said belts and being located to receive Sjlld. second roll.

A drawing frame for drawing roving as defined in claim 1, said belt guide member having a convex surface a acent t0 he r ll of Said second support means and ex-v tending transversely to said belts, said second roll being Thus, for example, with a predetermined intcr- Advantageously, the adjustment of the i positioned forward of said convex surface with respect to the travel direction of the roving.

4. A drawing frame for drawing roving as defined in claim 1, said belt guide member having a convex surface adjacent to the roll of said second support means and extending transversely to said belts, said convex surface continuing in a concave surface extending transversely to said belts, said second roll being positioned opposite to said concave surface.

5. A drawing frame for drawing roving, comprising a delivery roll, a top roll resting on said delivery roll, guide means for the roving to be drawn disposed ahead of said delivery roll with respect to the run of the roving and comprising a lower guide roll rotatable on a stationary axis, support means swingable about said stationary axis, a second roll mounted on said support means in spaced relation and parallel to said lower guide roll, a first endless belt looped around said lower guide roll and said second roll, a top guide roll, a weight link rotatably supporting said top roll and said top guide roll in spaced and parallel relation, a belt guide member connected with said link and disposed above said second roll, a second endless belt looped around said top guide roll and said belt guide member and having a lower run running along a run portion of said first endless belt extending between said lower guide roll and said second roll, and adjusting means connected with said support means for swinging same on said stationary axis and changing the position of said second roll relative to said belt guide means.

6. In a drawing frame for drawing roving of different length staple fibres, feed top and bottom rolls pressed toward each other to form a nip, top and bottom delivery rolls spaced from said feed rolls, the space therebetween constituting a drawing field, an endless belt looped around each of the feed rolls, a tensioning means for tensioning one of said belts, a belt deflecting means for deflecting said tensioned belt and located between the delivery and the feed rolls, an adjustable support for the deflecting means, a guide Within the loop formed by the other belt and disposed adjacent to the feed top roll, said guide having a convex surface extending tangentially from the periphery of the feed top roll in the proximity of the nip and continuing into a surface complementary to the surface of the belt deflecting means.

7. A drawing frame for drawing roving of different length staple fibres, comprising a pair of feed rolls forming a nip, a pair of delivery rolls spaced from the feed rolls, two endless belts each extending around one feed roll, said belts joining one another at the nip of the feed rolls for embedding the roving pulled into the nip, said belts advancing jointly towards the delivery rolls and disjoining at a point remote from said nip, and guide means acting between said feed rolls and said delivery rolls from either side onto the jointly advancing belts, said guide means comprising a guide having a convex surface portion adjacent to one feed roll and facing the jointly advancing belts, a transversely adjustable deflecting means urging said jointly advancing belts to slide along the convex surface portion for an adjustable range extending from the proximity of the nip to a selected point determined by the position of said deflecting means, the counteraction of said convex surface causing pressure between the jointly advancing belts while within'said range.

8. In a regulable apparatus for drawing strands of staple textile fibers of various approximate lengths, two opposed pairs of rolls for controlling the local speed of movement of the fibers of which the strand is composed, said pairs being spaced apart and the space between said pairs of rolls comprising a drawing field for the strands of fibers, each of the rolls of the rear pair, considered with respect to the movement of the strands of fibers, being feed rolls and having an endless belt looped thereabout, a belt guide located within the loop formed by one of said belts in contiguity to its feed roll and having a curved belt facing surface with a sense. of curvature similar to that of the adjoining roll portion, adjustable. means located within the other belt for pressing the said other belt toward the first belt, to force the. latter intosliding engagement with the curved belt facing surface so that the length of the path of the belts along the belt facing surface is altered and pressure is produced between the iblegis throughout an adjustable portion of the drawing 9. In a drafting arrangement for drawing strands of staple textile fibers of various approximate lengths, a bottom and top feed roll, a bottom and top delivery roll spaced apart from said feed rolls, each of said feed rolls having an endless belt looped thereabout, a belt guide located within the loop of one of said belts in proximity to said belt without deflecting or applying pressure thereto when the apparatus is adjusted for drawing long staple fibers, said belt guide having a recess facing said belt, adjustable means adapted to be received in said recess and located Within the loop of the other belt for pressing the other belt toward the first belt and pressing the belts into said recess so that the paths of the belts are altered and pressure is produced between the belts substantially in continuation of the pressure applied by the feed rolls.

10. In a drafting arrangement for drawing roving containing textile fibers of various approximate lengths, a feed top roll and a feed bottom roll, a delivery top roll and a delivery bottom roll spaced from the feed rolls, the space between said feed and delivery rolls constituting a drawing field for the roving passing between the top and bottom rolls, a first belt looped around said feed top roll and a second belt looped around said feed bottom roll, a belt guide located within the loop of one of said belts and mounted adjacent to the respective feed roll,

said guide having a convex surface facing the belt within whose loop the guide is located and receding from the belt in the forward direction of travel of the roving, adjustable means for pressing the other belt forwardly of the said guide toward the belt which extends around the guide to deflect the paths of said belts and to press the belt looped around the guide against the guide whereby part of the path of the belts is caused to conform to the convex surface of the guide, and pressure is produced between said belts and applied on the roving which pressure diminishes in the direction of the delivery rolls in dependence of the length of the engaged guide surface.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,092,631 Casablancas Apr. 7, 1914 1,697,737 Simon Jan. 1, 1929 2,037,836 Truslow Apr. 21, 1936 2,209,573 Louie July 30, 1940 2,239,863 Schlipp Apr. 29, 1941 2,304,885 Cobb Dec. 15, 1942 2,306,848 Toenniessen Dec. 29, 1942 2,471,057 Bird May 24, 1949 2,471,058 Bird May 24, 1949 

